Viral resistance and HIV treatment

Viral resistance and HIV treatment

Evolutionary Dynamics of Complex Networks of HIV Drug-Resistant Strains: The Case of San Francisco.

Over the past two decades, HIV resistance to antiretrovirals has risen to high levels in the wealthier countries of the world able to afford widespread treatment. The authors have gained insights into the evolution and transmission dynamics of ARV resistance by designing a biologically complex multistrain network model. Using this model, they traced the evolutionary history of antiretroviral resistance in San Francisco and predict the future dynamics. Using classification and regression trees, Smith and colleagues have identified the key immunologic, virologic, and treatment factors that increase antiretroviral resistance. Their modelling shows that 60% of the currently circulating antiretroviral-resistant strains in San Francisco are capable of causing self-sustaining epidemics, as each individual infected with one of these strains can cause on average more than one new resistant infection. It is possible that a new wave of antiretroviral-resistant strains that pose a significant threat to global public health is emerging.

Editors’ note: These modellers predict that a wave of NNRTI- (non-nucleoside reverse transcriptase inhibitor) resistant strains will emerge over the next 5 years in San Francisco due to HIV transmission from untreated individuals. They also claim that if the reproduction number (the number of infections that one person transmits) of wild-type strains is reduced below one in resource-constrained settings (which would normally see an epidemic decline), self-sustaining epidemics of NNRTI-resistant strains could arise. Whether their model’s predictions are accurate or not remains to be seen but clearly increased investment in resistance monitoring around the world is warranted as we scale up to universal access to antiretroviral treatment for all.